1. Field of the Invention
The present invention relates generally to the field of slurry transport systems and is particularly concerned with the use of concentrated brine as the fluid medium of transport.
2. Prior Art
The concept of transporting through a pipeline, pulverized solid particles suspended in a fluid medium dates back over 100 years to its use in the 1850's for placer mining operations. This is noted in the publication: The Transportation of Solids in Steel Pipelines, Colorado School of Mines Research Foundation, Inc. 1963. In 1891, a patent was granted to Wallace C. Andrews, for a method of pumping coal with water. In 1914, an operating system employing an 8-inch line was constructed to transport coal into London. The transportation of minerals in slurry form through pipelines is well-known in the art as evidenced by comprehensive references listed in: Slurry Transportation Bibliography, published by the Slurry Transportation Association, Washington, D.C. The bibliographic listings pp. 1-41 cover the transport of a variety of minerals, and particular reference is given to listings on pp. 19 to 29 covering the specific subject of coal slurry transport systems.
Although coal and other minerals recovered in remote areas are now being transported in some instances through slurry pipelines, it does not as yet constitute a major mode of transport. Because of our dire energy needs, and because of the abundant sources of coal existing in remote geographic areas, it is expected that transport of coal in slurry form through pipelines will become increasingly more important. Ease of handling, greater capacity, and lower costs, are some of the distinct advantages of slurry transport as compared to other means of coal transportation such as by railroad cars, tankers, and trucks. There is an inherently greater efficiency of transport that increases with volume and/or distance.
There are in existence today, several major slurry pipeline systems in the United States. These are summarized in an article by John F. Kiefner: Review of Slurry System Projects In The U.S., pp. 10-1, Proceedings of The International Technical Conference on Slurry Transportation, February 3-4, 1976, Battelle Memorial Institute, Columbus, Ohio.
The only coal pipeline now in operation is the Black Mesa pipeline, an 18-inch line which transports coal from the Black Mesa in Arizona to a power plant in southern Nevada, for a distance of 273 miles. This line delivers approximately 5 millions of tons of coal per year, at a cost estimated to be somewhat more than half the cost that would be incurred through use of rail transport. In addition to the Black Mesa pipeline, there are currently 6 long distance coal pipelines either now under construction or in the planning stage in U.S.
One of the major drawbacks in the use of slurry pipeline for coal transport, is the consumptive use of potable water resources, particularly in the western coal resource areas of U.S. It has been suggested that this environmental impact can be substantially reduced through the use of abundantly available saline groundwater.
In an article by T. K. Rice, T. M. Evans, M. Warner: Environmental Considerations of The Use of Saline Water in Coal Slurry Pipelines, pp. 3-3 to 3-17, Proceedings of the International Technical Conference on Slurry Transportation, February 3-4, 1976, Battelle Memorial Institute, Columbus, Ohio, it is noted that a coal pipeline moving 25 million tons of coal annually requires at its source, about 15,000 acre-feet of water per year. It is further noted that most of the country's coal reserves are located in western states and areas which are generally potable water poor. The authors indicate that saline groundwater generally underlays most of the United States. These waters, in varying quantities, salinity and degrees of accessability, contain at least 1,000 milligrams per liter (mg/L) and as much as about 35,000 mg/L of dissolved solids, with some of the major constituents being sodium chloride, sodium bicarbonate, calcium and sodium sulfates. It is suggested by the authors that one of the major environmental impacts of coal slurry pipeline operations, namely the consumptive use of potable water, can be substantially reduced by the use of saline groundwater.